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Z G Liang

Publications and source records attributed to Z G Liang.

16 recordsLinked to original sources
PubMed2000

Molecular cloning and characterization of functional domains of a human testis-specific isoform of calpastatin.

Human serum containing sperm-agglutinating antibodies was used to screen a testis cDNA expression library to identify the cognate antigens that may be responsible for this biological effect. The longest positive phage clone (1.9 kb) was sequenced and found to be a testis-specific isoform of calpastatin (tCAST). The testis-specific segment of tCAST is encoded by a single exon within intron 14 of the calpastatin gene. A unique protein isoform is produced that differs in domain structure from the somatic calpastatins (sCAST). Human sCAST most commonly has an N-terminal domain L plus the four functional calpain inhibitory domains. Human tCAST consists of a 40-amino-acid N-terminal T domain plus a part of domain II and all of domains III and IV from the somatic isoform. Our data show that the T domain can target cytosolic localization and membrane association of tCAST, whereas domain I of sCAST exhibits a nuclear localization function. Calpastatin is the endogenous inhibitor of calpain. The calpain/calpastatin system is involved in membrane fusion events for several cell types, and calpain has been localized to the sperm acrosome. We detected tCAST in human sperm and testes extracts by Western blotting with specific antisera. These observations suggest that tCAST may modulate calpain in the calcium-mediated acrosome reaction that is required for fertilization.

Amino Acid Sequence↗
PubMed1997

Colinear synthesis of an antigen-specific B-cell epitope with a 'promiscuous' tetanus toxin T-cell epitope: a synthetic peptide immunocontraceptive.

Carrier conjugation is commonly used to provide T-cell help for small, linear peptides containing antigen-specific B-cell epitopes. However, carrier conjugation is expensive, variable and often results in adverse side effects if the conjugate is administered repeatedly. To eliminate the need for carrier conjugation, we examined two synthetic peptides for their ability to elicit sustained antibody titres in female rabbits and baboons. One peptide (hC1-20) was based on the sequence of the sperm-specific isozyme of human lactate dehydrogenase (LDH-C4). This peptide stimulates helper T-cell responses. The other peptide (bC5-19:TT) was a chimera between an LDH-C4 B-cell epitope and a 'promiscuous' T-cell epitope from tetanus toxin which has been shown to bind to and stimulate many different major histocompatibility complex alleles. Both peptides were immunogenic in rabbits and baboons. The chimera elicited consistently high antibody titres and was immunogenic in 19/19 wild-caught female baboons. When 14 bC5-19:TT immunized baboons were mated, their fertility was reduced by 62% compared with controls (P < 0.02). This carrier-free construct can be incorporated into biodegradable microspheres which may provide long-term protection from pregnancy with a single dose.

Amino Acid Sequence↗
PubMed1994

Human testis cDNAs identified by sera from infertile patients: a molecular biological approach to immunocontraceptive development.

Sera from patients with known or suspected immunological infertility were used to screen a human testis cDNA library. A total of 59 sera detected 38 unique cDNA inserts of which four were testis specific by Northern blot analyses. One of these is a testis-specific isoform of calpastatin. Five additional clones, although not testis specific, were found to be testis abundant. The number and type of clones identified by these human sera suggests a possible aetiology for immunologic infertility. The testis-specific clones will be further characterized to establish their usefulness as contraceptive vaccine candidates.

Antigens↗
PubMed1991

Properties of an immunoglobulin binding factor from human seminal plasma.

A soluble factor (IBF) in human seminal plasma that binds serum immunoglobulins (Ig) of various species was purified to homogeneity by ammonium sulfate precipitation, preparative isoelectrofocusing, and gel filtration chromatography. The purified IBF interacted weakly with Fc and F(ab')2 fragments and not with Fab. It interacted with anti-Leu 11b and polyclonal anti-Fc gamma RIII antibodies, but not with other anti-Fc gamma R antibodies (32.2, IV.3 and 3G8). IBF is probably a non-glycosylated protein with isoelectric point ranging from 5.1 to 5.8. The estimated Mr of the purified native IBF is 27 kD, determined by sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-PAGE) under non-reducing condition. In its native form, IBF did not bind Ig or interact with anti-Fc gamma R antibodies. Following SDS-PAGE under reducing condition, IBF migrated as a single protein with an estimated Mr of 16 kD and interacted with Ig of various species and with anti-Leu 11b antibodies. When carboxymethylated, however, IBF did not bind IgG. The present results suggest that free sulfhydryl groups of IBF is required for Ig binding.

Antibodies↗
PubMed1989

[Study on follicle growth, ovulation and morphological changes of endometrium by ultrasonic and biochemical measurements].

Daily growth of the follicles before ovulation and the changes of the endometrium after ovulation were recorded in 16 spontaneous menstrual cycles by the ultrasonic and biochemical measurements. The mean diameter of the dominant follicle was 20 mm before ovulation, the mean volume 3.0 ml, and the growth rate of the follicles 1-3 mm/24 h. Ovulation occurred within 24 h of the luteinizing hormone peak and within 48 hours of the blood estrogen peak. The fact that the blood progesterone levels were higher on the day of the LH peak indicated that luteinization of the dominant follicles had already occurred prior to ovulation. Sonographic criteria of the endometrical tissue were obtained after the serial observation. According to the different sonographic appearances, the secretory phase of the endometrial tissue was divided into the early secretory phase, the middle secretory phase and the late secretory phase. The sonographic characterization of the endometrial tissue in the different phases as well as the thickness of the endometrium during the cycles were described. The clinical usefulness of the criteria of the different phases was to evaluate the subsequent luteal function, and facilitate the clinical management of the infertile women. The study confirms that ultrasound can provide a reliable measure in monitoring the follicular growth and ovulation, and observing the morphological changes of the endometrial tissue during the secretory phase. Thus the in vivo differentiation of the endometrial tissue during the secretory phase could be studied non-invasively by means of the ultrasound tissue characterization.

Adult↗
PubMed1986

Non-cross-reactivity of antibodies to murine LDH-C4 with LDH-A4 and LDH-B4.

The induction of infertility by immunization with the sperm-specific lactate dehydrogenase, LDH-C4, suggests its use in a contraceptive vaccine. Development of an immunological contraceptive for human use, however, requires that there be no cross-reactions with somatic tissues. We have demonstrated, using enzyme-linked immunoabsorbence, solid-phase radioimmunoassay, and competitive inhibition radioimmunoassay, that antisera to LDH-C4 is specific and does not cross-react with the somatic isozymes, LDH-A4 and LDH-B4.

Animals↗
PubMedDate not supplied

Immunoglobulin-Fc binding factor in human male reproductive organs.

Human seminal plasma, testis, seminal vesicle, epididymis, and prostate contain a component with an estimated Mr of 20 kD that binds human immunoglobulin-Fc. The factor did not bind goat-IgG-Fc, immunoglobulins of human, rat, mouse, goat, horse, or rabbit sera and did not interact with antibodies raised against Fc gamma receptors. The present findings show that this Fc binding factor in seminal plasma is a secretory product of the testis and accessory sex organs. It binds human Ig-Fc but does not meet the criteria of an Fc receptor. Additional IgG-Fc binding proteins with estimated Mr of 90, 88, and 86 kD were detected in the prostate, testis, and seminal vesicle, respectively.

Genitalia, Male↗
PubMedDate not supplied

Binding of a specific subclass of immunoglobulins by a human seminal plasma component.

Human seminal plasma contains a component that binds immunoglobulins (Ig). The Ig binding factor was purified by ammonium sulphate precipitation, preparative isoelectrofocusing and gel filtration chromatography and found to bind strongly human IgGl and mouse IgM. This seminal plasma component may possess immunosuppressive activity and may modulate the activities of the immunosurveillance system of the reproductive tract.

Animals↗
PubMedDate not supplied

Immunoglobulin binding factor of seminal plasma: a secretory product of human prostate.

To determine the source of the immunoglobulin binding factor (IBF) in seminal plasma, extracts of testis and accessory male sex organs were prepared and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot. The detection reagents used were human and mouse serum Ig, monoclonal anti-Leu 11b antibodies, and polyclonal rabbit anti-IBF antibodies. Of the tissues examined, only the prostate, including benign hypertrophy and adenocarcinoma, contained IBF. These findings suggest that IBF is a secretory product of the prostate.

Humans↗
PubMedDate not supplied

Prostatic specific antigen and immunoglobulin binding factor in human seminal plasma and prostate.

Antibodies raised against prostatic specific antigen (PSA) and immunoglobulin binding factor (IgBF) of human seminal plasma (SP) were used to localize the antigens in various tissues by Western blot. Both antigens were found only in the prostate, including benign prostatic hypertrophy and prostatic adenocarcinoma. The polyclonal anti-PSA antibodies stained five prostatic protein bands with estimated M(r) values of 10, 14, 22, 25, and 33 kD, whereas anti-IgBF antibodies stained a single 16-kD protein. No cross-reaction occurred between the two antibodies. When anti-PSA antibodies were used an additional protein with an estimated M(r) of 35 kD was detected in the extract of benign prostatic hypertrophy, but not with normal prostate or prostatic cancer. When SP and prostatic proteins were analyzed by SDS-PAGE under nonreducing condition and immunoblot with both antibodies, immunoreactive proteins with estimated M(r) of 125 and 140 kD, respectively, were stained, suggesting that both factors may be produced as an aggregated precursor molecule. Since IgBF was found only in the prostate, this component may be useful as a marker of prostatic tissue.

Animals↗
PubMedDate not supplied

Immunoglobulin binding factor in human seminal plasma: immunological function.

Human seminal plasma contains a protein with an estimated molecular weight of 16 kd that binds serum immunoglobulin gamma (IgG) and is named IgG binding factor (IgBF). Purified IgBF specifically suppressed pokeweed mitogen-induced lymphocyte blastogenesis, having little or no effect on lymphocyte blastogenesis stimulated with phytohemagglutinin or Concanavalin A; antibody-dependent cell-mediated cytotoxicity; natural killer cell activity; or complement-dependent cytotoxicity of antibodies against sperm. It would appear that IgBF may suppress activation of B cells in the male and female genital tract.

Antibody-Dependent Cell Cytotoxicity↗
PubMedDate not supplied

IgG4 binding factor in human seminal plasma identified as heavy chain of immunoglobulin.

Human seminal plasma contains a factor that binds human immunoglobulin G (IgG). The factor has an estimated M(r) of 50 kD and interacts specifically with human IgG4. It does not bind other subclasses of human IgG or IgGs of other mammalian species tested. The factor was purified by affinity chromatography on protein G column. The 50-kD component was eluted in the adsorbed fraction and immunostained with monoclonal antibodies against heavy chain (gamma) of IgG. Purified subclasses of human serum IgG were separated into heavy and light chains by sodium dodecyl sulfate polyacrylamide gel electrophoresis under reduced condition. The heavy chains of all subclasses of IgG bound IgG4. The present findings suggest that the 50-kD IgG4 binding factor of human seminal plasma is the heavy chain of IgG.

Animals↗
PubMedDate not supplied

Preparation and characterization of monoclonal antibodies against sperm-specific lactate dehydrogenase C4.

LDH-C4, the testis-specific isozymes of lactate dehydrogenase (LDH), is the predominant LDH isozyme in mammalian spermatozoa. Nine monoclonal antibodies against mouse LDH-C4 have been developed. These antibodies were tested for cross reactivity with LDH-C4 from human testis and with LDH-1-5 from mouse and human testes by immunoelectrophoresis, bio-dot, and western blot assays. The results showed that all monoclonal antibodies were specific to LDH-C4 only: they did not react with LDH-1-5 from mice, nor from humans. The immunologic localization of the monoclonal antibodies on capacitated sperm was observed by indirect immunofluorescent assay. On mouse sperm the antibodies were bound to the tail only, but on human sperm eight antibodies were bound to the postacrosome, some to the neck and to the mid-piece. Most of the antibodies belonged to the Ig G class.

Animals↗